I have experienced this problem several times in the past few years, both on a G4 PowerBook and Intel iMac. For no reason, Safari will stop updating my RSS feed counts in the Bookmarks bar. RSS still functions and will update whenever a particular feed is selected, but the parenthetical numbers for each feed or folder do not change.

The fix is simple and doesn't hurt any of your RSS subscriptions. Just quit Safari, remove the Database3 file located in ~/Library » Syndication, and then launch Safari again. I move mine to the Desktop and trash it only after I've successfully restarted Safari and confirmed the problem is fixed. Safari will create a new file in its place.

Easy enough, but I've never seen it anywhere else online, and have forgotten it myself a few times.

While this "fix" works most of the time, I've seen instances posted in Apple Discussions where despite trashing the database, as well as the 2 syndication plist, the count mechanism was not restored. Restoration came from an Archive and Install.

When you trash the database, all RSS settings are returned to default value, meaning you'll need to reset the Article Length Slider and any other custom adjustments for each feed. There's got to be an easier way to do this, but nothing yet from Apple.

Also, in Safari 3 Beta, my Article Length Slider no longer reverts to the Custom position for recently added feeds (I must have crossed a # threshold). Rather the slider stays at the default setting (fully opened). No remedy to this even though I trashed the database and the aforementioned plist files. I remind myself "this is beta". Strangely enough, if I revert to Safari 2, the same slider problem continues.

If you make an RSS feed (or subscribe to one) without uniquely tagged uniquely tagged articles, Safari will incorrectly show all articles ever published, which is a pain. Then it shows the same article over and over as the publisher tried to debug his feed, and you can't get Safari to delete the old ones sometimes just by refreshing. So, this manual removal of the Syndication database can be extremely useful if that happens.